1. Field of Invention
The present invention relates to a pixel structure of a liquid crystal display (LCD) and the method for fabricating the pixel, and a LCD panel. More particularly, the present invention relates to a pixel structure of a liquid crystal display (LCD) and the method for fabricating the pixel, and a LCD panel, using four photomasks to form the black matrix on the thin film transistor (TFT) array.
2. Description of Related Art
The TFT LCD panel mainly includes a TFT-array substrate with a TFT array, a color-filter substrate with a color filter array, and a liquid crystal layer between the two substrates, wherein the TFT-array substrate is formed by several pixels, and each pixel includes one TFT and one pixel electrode.
The conventional method to form the pixel structure of the TFT LCD needs five photomasks. The first photomask is used to define a first metal layer, so as to form a scan line and a gate electrode of the TFT. The second photomask is used to define a channel layer and an ohm contact layer of the contact layer. The third photomask is used to define a second metal layer, to form a data line and source/drain electrodes of the TFT. The fourth photomask is used to pattern a protection layer. The fifth photomask is used to pattern a transparent conductive layer, so as to form the pixel electrode.
In addition, the color-filter substrate is implemented with a photoresist pattern with three colors of red, green, and blue, but also implemented with a black matrix between the color photoresist patterns. The color photoresist patterns on the color filter substrate are with respect to the pixels on the TFT-array substrate, and the black matrix pattern is with respect to the metal lines on the TFT-array substrate.
However, as the trend for the TFT LCD having been developed toward a greater size in fabrication, it would confront many issues to be solved, such as decrease of yield rate and throughput. In this situation, if the number of the photomasks can be reduced, the number of photolithographic processes on the film layers can be reduced, and thereby the fabrication time can be reduced, the throughput can increase, and then the fabrication cost is reduced.